Thermodynamic switch



J. w. PHELPs THBRIODYNAI'IIG SWITCH 2 Sheets-Sheet' 2 F110@ July 14 1920 Patented Dec. 4, 1923.

JAMES 'W. PHELIfS, 0F CHICAGO, ILLINOIS.

THERMODYNAMIC SWITCH.

Application filed July 14, 1920. Serial No. 396,128.

To all wiowiaz't may concern Be it known that I, JAMES IV, PHELPS, a citizen of the United States, and a resident of Chicago, in the county ot' Cook and State of Illinois, have invented cert-ainY new and useful Improvements in a Thermodynamic Switch, of which the'following is a specilication. e

My in yention relates to improvements in electripgghermo cutouts and thermo-dynamic eleme s therefor, and has special reference to s ch cutouts particularly adapted for llas ing electric lamps and signs.

The object of my invention is to provide a thermo-dynamic cutout which shall be simple and substantial in its construction; which shall operate positively to illuminate brightly and then dim an electric lamp; which shall have a. thermo-dynamic element which shall be capable of being manufactured rapidly and cheaply; and which can be constructed of bare or covered resistance wire.

One especial object 4of my invention is to provide means whereby a relatively long resistance wire can be arranged in a small compass and whereby I am enabled to produce the required resistance with the use of a larger and lower resistance wire than formerly and produce the thermo units'at a 'less cost.

My-i-nvention resides in a covered thermal element surrounded with a resistance coil produced in the novel manner herein lescribed and arranged to short circuit the coil upon a pre-determined rise in temperature and to throw the coil into circuit upon a drop in temperature, thus upona rise in temperature permitting the currentto flow to light the lamps connected with the` device, and upon a drop in temperature placing the lamps and coil in series and thusdimming the lamps.

Furthermore my invention resides in the method of producing a resistance element which consists in winding either a bare or a covered resistance wire around a core made of some good insulation substance such as asbestos, and then winding the core thus produced around a suitable support therefor, such as the explansion element of Va thermodynamic switc If 'the resistance wire is bare it is -wound around lthe cord in spaced turnsthe oord being yielding enough and ,the wire wound tight enough to cause the Wire to sink part I have illustrated several applications of i this particular form ot' element. but this invention has special reference to a cutout connection in the forni of a combined plug and socket the element being arranged in the body of the connection between the end connections whether these connections are of the screw'threaded form shown, oi' other well known forms. y

For a clear understanding of my invention attention is directed to the accompanying drawings forming part of this specification, and in which: v y

Figure l is a fragmentary central longitudinal section of a thermo-dynamic cutout connection constructed in accordance with my invention, showing a lamp in the socket end of the saine; ,c

Figure 2 is Va longitudinal section of the thermo-dynamic element and its connections;

Figure 3 is a substantially central longitudinal section of the connection on the line 3 3 of Figure l;

Figure 4 is a cross section` of the connection on the line 4 4 of Figure l;

Figure 5 is an electric circuit diagram;

Figure 6 is a perspective view of the insulation cord showing a bare insulation wire wound thereon;

Figure 7 is a similar view showing a covered wire wound on the cord;

Figure 8 is a plan view of a combined screw socket block and a thermo-dynamic cutout;

Figure 9 is a. vertical section on the line 9-9 of Figure 8;

Figure 10 is a plan view of a thermodynamic cuto'utfmounted on an insulation block and adapted to be interposed in a. circuit; and

Figure 11 is' a transverse section on the line 11-11 of Figure 10.

In said drawings, l is a thermo-dynamic element consisting of a curved bar or strap ranged to Contact. as the bar expands, with,

a fixed contact 5 and to be separated from said contact and break the Ycircuit as the bar contracts.

This thermo element is, in the preferred form of connection, mounted in a suitable opening 6 provided in a cylindrical shellf like body @which body carries at itsends suitable devices for readily inserting the devi ce as a whole in an electric circuit. At one end I provide, as shown in Figures 1 and 3, a screw plug 8 by which the device can be connected in an ordinary screw socket for the supply of the current. At the oppo; site end I provide a screw socket 9 by means of which current can be readily taken off as for the lamp 10.

The bar or strap 2 is rigidly mounted within and upon the body 7, which is pref.n erably made of porcelain or some similar rigid insulation substance, by clamping bolts 11 and 12 at its ends. 'The bolts pass through suitable openings in walls or shoulders 13 and 14 which are arranged beneath the ends only of the bar. 'Ihe middle portion of the bar is curved away from the plane of said shoulders and is free yto take its shape as determined by its temperature.

The stationary contact 5 is carried by the inner end of an adjustable screw 15 which is mounted in a suitable opening in the wall of the body 7 and is carried bv a connecting plate or strap 16 secured within the opening 7 opposite to the element 2. This connector is secured rigidly to the body by screws 17. The contact screw 15 is mounted in a screw threaded openingVV in thelconnector whereby it is adapted to be adjusted from and toward the element 2. The screw 15 is adapted to be held in the adjusted position by a compression spring 18 mounted between the head of the screw and the plate 16, which thus applies friction to the screw and holds it rigidly in position.

The connecting strap 16 extends out into the socket 9 and its end 16 is bent over to form the contact at the bottom of the socket with which the contact at the center of the base of the lamp connects. Just below the end 16 I provide an insulating washer 19 which is provided with an opening through which the end of the strap is passed before it is bent over and by which the washer is held in place. 1 Y

At the opposite end of the device I provide a connecting plate or strap 21 which has maracas its inner end clamped beneath the adjacent end of the bar 2 and the shoulder l4 by the clamping bolt 11 and its outer end 22 is projected through an opening 23 in a porcelain insulation plug or member 24 which closes the body of the device at this end. The end 22 of the strap 21 is bent over upon the outer surface of the plug 24 to form the central contact at this end of the device. The threaded shell 8 forms the other contact, as isy usual. The plug 24 is provided with a central projection 25 on its inner end which fits within a central opening in the-screw plug shell 8 and is held central thereby.

Als an outer protector to the device I provide a cylindrical shell 2G made of fibre or some other suitable material adapted to slide over the socket 9 and the bodyv of the device so that none of the screws or contacts are exposed. I provide the shell with an opening 27 in the side wall arranged immediately over the screw 15 so that this screw can be adjusted without removing the shell, to adjust the periodic flashing effect of the device.

To complete the return circuit I connectI the two shells 8 and 9 by thin metallic connecting strips 28, preferably one arranged at each side, and which serve to tightly hold the said members in place on the body. the ends of these strips being connected to the shells preferably by soldering.

As so far described andas illustrated in Figure 5, the current enters the device through the connector 21, passes to the bar 2 and when the circuit is complete at the contacts 4 and 5, through the screw 15 and strap connection 1G to the lamp 10 and returns through shell 9, and the connecting straps 28 to the shell 8 at the other end.

'Ihe resistance coil 3, which serves to heat the bar 2 and close the circuit at the contacts 4 and 5, is preferably made of resistance wire 29 which is wound on a flexible insulation cord 30, preferably made of asbestos or some similar non-inflammable material. When bare wire is used the' turns 31 of the wire 29 are wound separated from each other to avoid short circuiting them and I retain them in such separated con dition by winding the wire on the cord under sufficient tensionto cause the wire to imbed itself either wholly or partly in the surface 'to permit the air to circulate around the wires so that the coilwill lcoo'l promptly.

In Figures 8 and 9 I have shown another application of the control element. In this instance a lamp socket 39 is mounted on a base 40 which is provided with two upstanding walls or projections 41 to which the ends of the thermostatic element 2 are securely bolted. A third upstanding projection or wall 42 carries the connecting strip 43 which is bolted thereto by a fastening screw 44 and an adjustable contact screw 45. The screw 45 is arranged `opposite to the middle portion of the bar 2 similar to the screw 15 in the first form. One end ofthe connecting strip 43 is provided with a binding screw 46 for connecting a lead wire 47 and the other lead is connected beneath a binding screw 48 which is mounted on the outer end of a connecting strip 49 which leads in to the center of the `socket 39. The metallic shell 50 of the Socket is connected to one end 51 of the bar 2' to which one end of the resistance coil 3 is also connected. The opposite end of the coil 3 is joined to the connecting stri 43.

The operation in t is instance is similar to that already described, the current passes X into the device Ithrough the connector 49,

then through the lamp or whatever device is connected in the socket 39, then to one end of the bar 2. From this point it either passes through the resistance coil tothe connecting bar 43 and so out of the device, or it passes direct through the bar 2 to the bar 43. This passage of the current through the resistance coil heats and expands the bar and closes the direct circuit through thebar 2 and the bar 43, thus shunting the resistance and causing the lamp to flash. The resistance wire being thus cut out it cools off and soon the bar contracts and opens the direct circuit at the contacts 4 and 5.

In Figures 10 and l1 I have shown one of the thermal elements mounted on an insulation base 52. The ends of the bar 2 are bolted firmly to the base and the center of the bar 2 is bowed up. Over the middle portion of the bar I provide a U-shaped bridge or support 53 to carry the adjustcontact 5. The construction and action of the thermostatic element is exactly as in the formerlcases, viz, the expansion and contraction of the bar 2 serves to cut out and in the resistance coil 3 and consequently the tric switch within the .and curved laterally ing screw 54 which carries at its end the I contacts, that the other contact is also mounted on a part rigid with the base, that consequently vibrations will not affect the operation of the device. In kconsequence of this the flashing of the lamp or lamps controlled by the device is positive and certain and it is substantially impossible-for the device to either get out of order or to burn out,

which frequently occurs with flashing de? vices which parts. v As many modifications of my lnvention `have mechanically movable will readily suggest themselves to one skilledY in the art I do not limit or confine my invention to the specific structures or arrangements of parts herein shown and described.

.I claim: A flashing electric connection comprisin a cylinder of insulating material provided at one end with a 'screw socket and at the other end with a screw plug, a thermo eleccylinder comprising mounted at its ends between its end s, a heating coil wound around said bar, one end of the coil connected to one end of the bar, a stra connection member clamped to said end o? the bar and extended to form the center contact for said plug, a rigid metallic bar opposed to said curved bar, an adjusting contact screw mounted in said rigid bar opposite to the middle portion of Said curved bar for making and breaking, connection therewith, the opposite end of said coil connectedV to said rigid bar, said rigid bar bea metallic bar rigidly JAMES W. PHELPS.

Witness T. D. BUTLER.

ing extended at one end to form the center` 

